Tuned telephone receiver



vPatented Dec. 25, 1923.

UNITED STATES PATENT OFFICE.

HUGO GERNSBACK, F NEW YORK, N. Y., ASSIGNOR TO RADIO INDUSTRIES CORPORA- TION, OF NEW YORK, N. Y., A CORPORATION 0F NEW YORK.

TUNEID TELEPHONE RECEIVER.

- Application led March 17,` 1923. Serial.` No. 625,702.

To all whom. it may cof/wem:

Be it known that I, HUGO GERNsAoK, a citizen of the United States of America, and a resident'of New York city, county and State of New York, have invented cert-ain new and useful Improvements in Tuned vention is to enable the matching or pairing of the receivers in a simple. and practical manner and in a way which can be readily performed after the receivers are assembled in condition for use.

Another important object of the invention is to provide a receiver particularly suited for loud-talkers and capable of adjustment to allow for increased action of the diaphragm resulting from loading7 of the actuating magnet.

Further objects of the invention are to effect savings in the cost of construction, to provide betterl protection for the more delicate parts of the instrument and to improve the acoustic' characteristics.

In the accompanying drawing there is illustrated a practical embodiment of the invention, wherein theforegoing and other objects are attained, but it is to be understood that the structure may be modified invarious/respects without departure from the broad spirit and scope of the invention as hereinafter definedl and claimed.

Figure 1 in the drawing referred to is .a perspective view of one of the receivers with parts broken away and appearing in section; Figure 2 is' an enlarged cross sectional brokenA View; Figure 3 isa fragmentary sectional view lsimilar to lFigure 2, showing the diaphragm adjusted in closer relation to the magnet; Figure 3 is a broken section illustrating the diaphragmn adjusted to a greater degree of clearance as for use in loud-talker operation; Figures 4, 5 and 6, are fragmentary sectional viewsof modified forms of the resilient diaphragm support.

The case of the instrument is shown in the form of a cup 5 closed at the back and havring an ear cap or cover 6 adjustably attached over the f ront or open "side of the same by a screwthreaded joint 7.

The actuating magnet 8 which is housed within the case is shown as of tripolar construction having a centrally disposed polar projection 9 and two side pole pieces 10.

The diaphragm 11 is supported and adjusably positioned with respect to the actuating magnet by a resilient element shown in the form of a ring 12 of highly elastic material, such as pure Para rubber, interposed between the back of the diaphragm and the rim or edge of the cup. The cap or cover has an Yinterior annular shoulder 13 engaging over the edge of the diaphragm and extending both outwardly and inwardly above the area of contact between the supporting ring and diaphragm so as to provide a firm seat for the diaphragm and enable the application of a compressing force without distortion of the diaphragm. Thus in the illustration it will be seen that by turning the cap down over the case the resilient diaphragm supporting annulus will be compressed and so enable a. very exact adjustment of the diaphragm toward the magnet face or faces.

In the first form of the invention illustrated the diaphragm supportingv ring is shown as substantiallyT T-sha e incross section, with a head having a decidedly rounded crown, fiatat the under side for a. full bearing on the face of the cup and with the dependent portion seated in an annular groove 14 provided in the face of the cup.l The crowned head of the ring is shown as of less width than the face of the cup wall so that it will not under compression expand beyond the edges of the cup. The seating of the dependent rib within the grove holds the supporting ring accurately located under all degrees of compression and this construct-ion also provides a depth of elastic- 'materlal which allows for the full necessary range of adjustment of 'the diaphragm. 1

In the present disclosure I have illustrated several of tlhe different ways in which the resilient diaphragm support may be constructed. In the y first 'modification illustrated in Figure 4, the head'or contacting face of the support is ribbed as indicated at v to fit over a corresponding rib 17 on the face of the case.

In Figure 6 the resilient diaphragm support is illustrated as a ring 18 which is of circular cross section and tubular in form, seated within 'a substantially `semi-circular groove 19.

In all forms the diaphragm support has a range of compressive adjustment at least equal to the difference between the maximum and minimum permissible clearance between the diaphragm and pole face or faces of the actuating magnet. This enables the diaphragm to be set at the best or more effective pointwithin the scale of operative relation to the magnet.

Because of the fact tha't'the diaphragm is positioned by the resilient support it is possible in this invention to face od the magnet poles and the rim or edge of the case in the same plane, substantially as indicated in the drawing. yllhis means that after assembly of the magnets in the cases the magnet poles and cases can both be finished od in a single grinding or facing operation. This construction also results in greater accuracy and eiciency since no minute measurements and adjustments are necessary to establish a nely adjusted relation between the magnet poles and rim of the cup.

llt will be seen from the foregoing that by simply turning the ear cap the diaphragm may be adjusted toward or away from the actuating magnet to vary the tone and other characteristics or the receiver. rlhis enables the receivers to be very easily tuned either for the purpose of matching them or for bringing in special signals, such as the higher pitched notes, for instance, which only become audible upon a very close adjustment of the diaphragm. The resilient support provides a practical air-tight seal for the receiver case, preventing rust, corrosion or other injury of the magnet parts. This air-tight construction also appears to improve the acoustic properties, producing a clear agreeable tone, the pitch of which can be readily varied to suit the individual user.

- The resilient support gives the diaphragm a freedom of action which particularly suits the receiver to the exactingrequirements of loud-talkers, permitting the diaphragm to flex easily and through the necessarily greater ranges required in loud-talker operation and by the simple adjustment disclosed, the diaphragm can be quickly adjusted to increase the spacing so that the diaphragm will vibrate free of the magnet no matter to what extent the magnet is loaded.

Leraren Another important feature of the invention disclosed is that in each instance the diaphragm remains in its adjusted relation without provision of set screws or other special holding means, the resiliency of the diaphragm support operating as an automatic lock for retaining the parts in each adjustment.

What l claim is:

1. ln telephone receiver, a hollow case, a magnet within thecase having a pole piece for actuating the diaphragm, the ed e of the case and the tace of the pole piece eing iinished in substantially the same plane whereby both may be faced ed in a single operation, a diaphragm. overstanding the edge of the case, a resilient support for the diaphragm interposed between the diaphragm and the edge of the case and a screw cap adjustably engaged with the case over the diaphragm and adapted by its adjustment on the case to compress the resi ient support in varying degrees and to thereby adjust the relation of the diaphragm to the pole face of the magnet.

2. lin a telephone receiver, a case, a magnet in said case arran ed with its pole tace in the plane of the edgge vof the case, a diaphragm, a resilient support for the diaphragm seated in the edge of the case and to enable variable spacing of the diaphragm with` respect to the magnet through the range of practical operativeness of the magnet and retaining means for the diaphragm adjustable with respect to thecase for varying the compression of the resilient diaphragm support.

3. .lin a telephone receiver, a casing having an annular wall with a groove in the top tace of the same, a diaphragm su port of highly resilient material, substantially T- shaped in cross section, having the dependent portion thereof engaged in said groove and the head portion of the same bearmg on the top face ot the annular wall at opposite sides of the groove therein, a diap ragm bearing on the head portion of said resilient su port and a retainer for vsaid diaphragm adjustable with respect to the case for the purpose of varying the compression of the HUGO GERNSBACK. 

